Lathe-dog



(No Model.) O. W. SHARTLE.

LATHE DOG. No. 411,620. Patented Sept. 24, 1889.

F J I Witnesses: Inventor Attorney N. PETERS. PMWUIMgn-aphar. Walhinnnnnnn C,

UNITED STATES PATENT OFFICE.

Ul-IARLES XV. SHARTLE, OF MIDDLETOlVN, OHIO.

LATHE-DOG.

SPECIFICATION forming part of Letters Patent No. 411,620, datedSeptember 24:, 1889.

Application filed April 8, 1889,

To aZZ 2072,0122, it nmy concern.-

Be it known that 1, CHARLES 'W. SHARTLE, of Middletown, Butler county,Ohio, have invented certain new and useful Improvements in Lathe-Dogs,of which the following is a specification.

This invention pertains to dogs to be employed in lathe-work and similarwork where round articles are to be grasped and rotated.

My present improvoments will be readily understood from the followingdescription, taken in connection with the accompanying drawings, inwhich- Figure 1 is a perspective view of a lathedog embodying myimprovements; Fig. 2, a face view of the same; Fig. 3, a face view ofthat portion of the dog at which the jaw is pivoted, the jaw and itscoverbeing removed Fig. l, a perspective view of the pivot-jaw inreversed position to expose the trunnion upon what would be the lowersurface of the jaw viewed under the conditions upon which Figs. 1, 2,and 3 are made; Fig. 5, aview of the jawcover removed; Fig. 6, avertical transverse section of the stock in the plane of the axis of thejaw-pivot; and Fig. 7, a vertical longitudinal section of the dog in theplane of the pivot'of the jaw, this view showing the parts reversed inposition--that is to say, the cover K is below, as if the dog shown inFig. 1 were turned over, so that the tail 0 bent downwardly. Figs. 3,4:, 5, 6, and 7 are upon an enlarged scale.

In the drawings,A indicates the usual stock r provided with an eye toreceive the work which the dog is to drive; B, a tail projectingradially therefrom to serve in the lathe in r0 tating the dog throughthe medium of anordinary drivingstud projecting from the faceplate ofthe lathe; O, atail projecting radially from the stock opposite to thetail B, and turned at right angles to the general plane of the stock,this tail being adapted to engage one of the usual slots in thefaceplate of a lathe; D, a pair of convergent set-screws screwed throughthe stock, one upon each side of the tail 0, these setscrews projectinginto the eye of the dog the axes of the two screws intersecting at apoint eccentric to the eye of the dog, such point being located betweenthe center of the eye and that wall of the $eria1No. 306,475. (Nomodel.)

.eye which is toward tail B; E, that portion of face of the stock overthe recess F, this covered recess being dovetailed at its side walls andopen toward the eye of the dog, so that the plate can he slid into thecover-recess and form a roof for the recess F; L, a pivot-block pivotedin the recess F and presenting a serrated face to the eye of the dogfacing toward the setscrews .D, the heel of this block being shaped tofit the wall H of the recess F, so as to take a bearing of oscillationtherein; and M, a trunnion integrally formed with and projecting fromone face of this jaw concentric with its heel-surface and adapted to fitwithin the pivot-hole G.

This dog is a self-gripping affair and the set-screws D are onlyrequired to serve in ad' justing the size of the dog, so to speak.Therefore these set-screws may be thumb-screws. Assume that theset-screws are entirely absent and that a cylindrical piece of iron, aslarge as can be gotten into the dog, he inserted in the eye of the dog.If an attempt be made to rotate this piece of iron that attempt willcause a partial rotation of the jaw upon its pivot and will in anobvious manner cause that jaw to exerta biting grip upon the piece andprevent its further rotation in the eye of the dog. This occurs witheither direction of rotary motion. It is further obvious that if thepiece of work in hand he a trifle smaller than that just assumed thepartial rotation required of the pivoted jaw before its forcible gripwould take place might be greater than the dimensions of the recess Fwould permit, in which case the jaw would not grip the piece; hence thenecessity of the set-screws for adjusting the practical size of the eyeto properly conform to the size of work in hand. The object of havingthe set screws diverge to a point eccentric to the eye of the dog is toenable these screws to be moved farther inwardly, when very small workis in hand, without the points of the setscrews coming in contact witheach other.

The working strains upon the pivot-block are met by the heel of theblock bearing in the wall H of the block-recess, the trunnion being freefrom strains and serving as a mere expedient to keep the block fromfalling out of the recess when not under strain. The cover-plate is heldin the recess J by mere friction and can be readily removed. The officeof' this cover-plate is to prevent the trunnion from leaving thepivot-h0le.

While this jaw grips with enormous force, and while no wrench is neededin applying the dog to the work, it is still found in practice that thedog does not mar finished work to any such extent as is the case withordinary dogs engaging the work by powerful setscrews. It is desirablethat the serrated face of the pivoted jaw engage fairly lengthwise alongthe piece of work in hand. .Oonsequently, when cylindrical work is to bedriven, the serrated face of the jaw should be parallel to the axis ofthe jaw; but such a jaw as this would bite at one end of the serrationsonly when applied to tapering work. The dog would thus have a tendencyto work off the same as is the case with ordinary set-screw dogs. In myimproved dog, however, this trouble may be avoided by using a pivotedjaw whose serrated face is at an angle to the axis of the jaw, so thatthe face will have a fair hearing on the taper work in hand. The

straight and the other one bent, permits of the same dog bein used forstud-driving or slot-driving, and the presence of the extra tail whenone only is used for driving serves in protecting the comparativelylight setscrews from being accidentally engaged by a driving-stud on theface-plate, and the two tails may also be used at once in connectionwith two driving-studs on a face-plate as a means for equalized driving.

I claim as my invention 1. In a lathe-dog, the combination,substantially as set forth, of a stock having one or more driving-tailsand an eye, a pair of convergent set-screws, and a jaw pivoted in thewall of the eye and presenting'a serrated face intosaid eye opposite tothe set-screws.

2. In a lathe-dog, the combination, substantially as set forth, of astock provided with one or more driving-tails and with an eye, a pair ofconvergent setscrews, a recess in the wall of the eye opening toward oneface of the dog, a cover-recess at the open face of said first-mentionedrecess, a removable coverplate fitting said recess, and a jaw pivoted insaid first-mentioned recess and presenting a serrated face in the eye ofthe dog opposite to 7 said set-screws.

3. In a lathe-dog, the combination, substantially as set forth, of astock provided with an eye and with two oppositely-projecting radialCHARLES WV. SHARTLE.

Witnesses:

W. H. TODHUNTER, J. H. PAINE.

